Surface Acoustic Wave (SAW) filters are compact, cost-effective RF filtering components that utilize mechanical waves propagating along the surface of piezoelectric materials. By converting electrical signals to acoustic waves and back, SAW filters achieve precise frequency selection with steep roll-off characteristics. They play a critical role in modern communication systems by enabling spectral efficiency, noise suppression, and signal integrity maintenance in wireless devices, automotive electronics, and industrial equipment.
| Type | Functional Characteristics | Application Examples |
|---|---|---|
| IDT-Structured SAW | Standard interdigital transducer design with <3 GHz operating range | Mobile phones, Wi-Fi routers |
| Dual-Mode SAW | Higher Q-factor through resonator coupling | 5G NR frequency bands (n77/n78) |
| Temperature-Compensated SAW (TC-SAW) | 0.5 ppm/ C stability using layered substrates | Automotive radar (76-81 GHz) |
| Miniature SAW (M-SAW) | 0.5-2.0 mm package sizes for IoT devices | Bluetooth LE modules, wearables |
Typical SAW filter construction includes:
Advanced variants incorporate temperature compensation layers (SiO2/Ta2O5) and reflector bars to enhance frequency stability and stopband attenuation.
| Parameter | Description | Importance |
|---|---|---|
| Center Frequency (f0) | 100 MHz - 6 GHz range | Determines application compatibility |
| Bandwidth (BW) | 0.5-15% of f0 | Impacts data rate capabilities |
| Insertion Loss | 1.5-15 dB | Affects signal strength |
| Attenuation Slope | 10-100 dB/MHz | Measures selectivity performance |
| Power Handling | 100 mW - 5 W | Limits transmitter integration |
| Temperature Stability | 50 ppm/ C (standard) | System reliability factor |
| Manufacturer | Representative Product | Key Features |
|---|---|---|
| Murata Manufacturing | SAWF9BAF420M4A1 | 2.4 GHz WLAN filter, 0.9 dB loss |
| TDK Corporation | KC5030S108MB1 | Sub-6 GHz 5G filter, 1.2 dB insertion loss |
| Skyworks Solutions | SAW-8851417 | Multi-band cellular filter, 1.8-2.7 GHz |
| Infineon Technologies | B11243-F108 | Automotive-grade TC-SAW for 80 GHz radar |
Key selection criteria:
Example: For LTE Band 7 (2.6 GHz) applications, select TDK's KC5030S108MB1 with 110 MHz bandwidth and 1.2 dB loss in 0.5x0.5 mm package.